Michael J. Spangler
01-29-2013, 01:01 PM
http://www.mcmaster.com/#expandable-laps/=l82y9e
So I just used one of these for lapping out my .401 die to .403.
It worked awesome. I started with a 3/8" through hole expandable lap. It expands to 15% over its original size.
My machinist buddy helped me with it so it was a pretty solid set up. He put the die in a collet on a fixture on the table of his Bridgeport then he chucked the lap in the mill, lied it up and went to town. We started with too fine of a grit compound and worked our way up to 45 micron which pretty fast.
I believe it was a diamond compound.
Definitely worth the $ if you want super precise control and a concentric sizing die.
I spent about $3 on a wooden dowel and probably as much on some cheap sandpaper to try to lap it with a hand drill. I could have spent the $7 on this lap in the first place. Definitely worth it.
So I just used one of these for lapping out my .401 die to .403.
It worked awesome. I started with a 3/8" through hole expandable lap. It expands to 15% over its original size.
My machinist buddy helped me with it so it was a pretty solid set up. He put the die in a collet on a fixture on the table of his Bridgeport then he chucked the lap in the mill, lied it up and went to town. We started with too fine of a grit compound and worked our way up to 45 micron which pretty fast.
I believe it was a diamond compound.
Definitely worth the $ if you want super precise control and a concentric sizing die.
I spent about $3 on a wooden dowel and probably as much on some cheap sandpaper to try to lap it with a hand drill. I could have spent the $7 on this lap in the first place. Definitely worth it.